Due to increasing needs for bandwidth, modern computer and communication networks are placing increasing reliance on optical signal transmission through fiber optic cabling. While fiber optic cabling is very efficient for transferring data, such light signals cannot, as yet, be effectively used to process data. Therefore, many existing networks use fiber optics for transmitting data between nodes and silicon chips for processing the data electronically within the nodes.
Electro-optic circuitry, such as fiber optic transceivers, which convert light signals from a fiber optic cable into electrical signals, and vice versa, are used as the interface between a fiber optic line and a computer node. A typical transceiver includes a substrate and one or more electro-optic (also referred to as opto-electronic) semiconductor devices mounted on the substrate. These electro-optic semiconductor devices can include optical detectors for converting light signals received over the fiber optic cables into electrical signals or optical emitters for converting electrical signals from the semiconductor devices into light signals. Such electro-optic devices are referred to herein as photonic devices. Typical examples of photonic devices include, but are not limited to optical emitters (which can include LED's, side emitting lasers, VCSEL's or other laser devices) and optical receivers. These photonic devices can be incorporating into a varying array of optical transmitter, receiver, and transceiver implementations. Such devices are widely available in a variety of standard formats. For example, a number of fiber optic transceivers are commercially available from Hewlett Packard, AMP, Sumitomo, Nortel, and Siemens.
In one common implementation, photonic device emitters and transmitters are mounted in “TO” can packages, which form part of emitter, receiver, and transceiver implementations. “TO” can packages are can-shaped cylindrical housings (constructed in accordance with the industry standard “TO” sizes specification) that can contain electro-optic devices such as are available from a wide variety of manufacturers. Examples of standard TO can package sizes include, but are not limited to TO-3, TO-5, TO-18, TO-39, TO-46, TO-52, TO-72, and TO-99. “TO” can packaged devices are large, bulky, roughly cylindrical devices constructed to be compatible with standard format MSA (multi-source agreement) optical modules. In one standard implementation, two “TO” can packaged devices are soldered to electrical connections on a standard PCB (printed circuit board). In a transceiver implementation, one “TO” can package includes a transmitter (laser) and another “TO” can package includes a receiver optical device. The PCB includes a plethora of non-integrated sub-systems and separate components that are electrically connected to facilitate optical to electrical conversion and vice versa. The sub-systems and separate components are also connected to “back end” electrical connectors of the PCB that can be plugged into compatibly formatted plug receptacles on other electrical components (e.g., computers, routers, switches, and/or other compatible components). Alternatively, the back end electrical connectors of the PCB are formatted as solderable connections that are soldered to other compatibly formatted electrical components (e.g., computers, routers, switches, and/or other compatible components).
FIG. 1 illustrates a figurative cross-section view of one conventional optical module implementation configured in compliance with an SFP format. A connector jacket 103 encloses a TO can package 101 that is wired to a PCB 105 having a plurality of components 107 thereon. The back end 108 of the PCB is depicted in the pluggable format having electrical contacts (also referred to as edge connectors) spaced, sized, and positioned for plugging into a compatible receptacle.
Commonly, the optical and electronic components are arranged in a module jacket to facilitate the easy interconnection of the optical and electronic components with the optical fibers. In common usage, the TO can pakages are arranged relative to a connector apparatus in a specified configuration which is in accord with one of a number of standard configurations. Such configurations are referred to herein as connector formats or, alternatively, just formats. By the TO can packages of a module in accord with one of the common formats, optical fibers configured in accordance with the same format can be interconnected to the TO cans of the module. Such optical modules are commonly arranged in formats complying with one of a plurality of standard connector formats. Commonly, the fibers are held by ferrules which facilitate easy interconnection with compatible modules. The ferrules can be configured to hold single fibers or configured to hold an array of fibers bundled together in the ferrule in accordance with a number of standard formats. For example, in one implementation a parallel array of 12 fibers bundled together in a common ferrule. Among the problems with such systems is that the large size of TO can packages limits the miniaturization possible in such modules.
As described above, National Semiconductor has developed a family of integrated opto-electric assemblies for interconnecting optical fibers to electrical devices. Some examples of such assemblies are described in detail in U.S. patent application Ser. No. 09/713,367, entitled “Miniature Opto-Electric Transceiver,” by Peter Deane, filed on Nov. 14, 2000; U.S. patent application Ser. No. 09/922,358, entitled “Miniature Semiconductor Package For Opto-Electronic Devices,” by Nguyen et al., filed on Aug. 3, 2001; and U.S. patent application Ser. No. 09/922,598, entitled “Techniques For Joining An Opto-Electronic Module To A Semiconductor Package,” by Nguyen et al., filed on Aug. 3, 2001 each of which are incorporated by reference herein. These and similar opto-electric assemblies have the capacity to replace the large TO can packages and PCB's used in conventional implementations. The integrated opto-electric assemblies are more reliable and have the capacity to include a much high circuit density than is possible using the TO can package and PCB combinations of the prior art. The integrated opto-electric assemblies of the present invention are also much smaller that the TO can packages and PCB's of the prior art.
FIG. 2 illustrates the size disparity between opto-electric assemblies 201 of the type described above and standard format SFF module 202 constructed using TO can packaged devices (not shown) and PCB 203. Although this degree of miniaturization is extremely advantageous, in many implementations it presents some integration difficulties with respect to existing formats. If used without adaptation, the depicted opto-electric assemblies cannot be used to implement many of the existing standard connector formats. Simply put, the small size and miniaturized format of such opto-electric assemblies 201 make them incompatible with many existing standard format modules. As a result, there is a need for an optical connector module (OCM) that can harmonize the integrated opto-electric assemblies 201 with existing connector formats. Such an OCM should be able to electrically and optically interface an integrated opto-electric assembly (including an integrated optical sub-assembly (OSA) and chip sub-assembly (CSA)) with a plurality of existing connector formats. It would be further advantageous, if for example, the OCM can interface the integrated opto-electric assembly with many existing legacy formats (such as MPO, MTP, MU, MT-RJ, MT-BP, and other standard formats including, but not limited to SFF and SFP formats).